Tracking Needs-Based Community and Specialized Services of Young Adults and Their Parents Before and During a First Episode of Psychosis (FEP): Highlighting Intervention Trajectories in FEP

Aim

This article aims to document 10 service trajectories of young adults (YA) and their parents, informed by healthcare professionals (HP), before and during a first episode of psychosis (FEP).

Design

Based on a crisis model perspective of the Life Course Theory (Elder; Elder and Shanahan) developed by Carpentier and White, and adapted to the current context to track community and specialized services trajectories. Thematic analysis was used to code responses to open-ended questions around the need for help and accessing services by young adults affected by a psychotic disorder, and their parents.

Setting

In collaboration with FEP clinics, setting of choice by YA and their parents.

Participants

5 YA, 12 parents, and 6 HP.

Results

10 individual service trajectories grouped into 3 distinct types of trajectories (optimal, typical, and complex) based on grouping 5 similar characteristics, highlighting service access complexity and early intervention in FEP.

Conclusion

This study is the first of its kind to examine the experiences of those who seek needs-based community and specialized services leading up to and during a FEP. Findings provide key insights related to early intervention in FEP and recommendations on improving access to such services in Quebec.

[Sharing information and respecting confidentiality: Standards for improving the quality of mental health services]

Objectives Collaboration between family caregivers and professionals plays a critical role in the recovery of the person living with a mental health disorder. However, collaborative practices between family caregivers and professionals are impeded by issues relating to confidentiality, particularly in connection with bidirectional information sharing between the parties involved. In doing so, these issues affect the quality of mental health services. Method A qualitative study was conducted with 19 family caregivers and 19 mental health professionals from 2 Quebec regions[2] in order to identify issues related to information sharing and confidentiality from their combined perspective. The Photovoice method was used and individuals semi-directed interviews were conducted with the 38 participants. Results Confidentiality and the refusal of the person living with a mental health disorder to consent to share information remains important and current obstacles in mental health practises. The organization of mental health services should ensure better integration of family caregivers into care teams so that they can contribute to the person's recovery and thus receive all the support and information they need to exercise their role. This study shows that family caregivers have different information needs in order to carry out their role and accompany the person living with a mental health disorder, including the need for general and non-confidential information to better support the person. While respecting the fundamental rights and autonomy of the person, who is free to consent or not to sharing information concerning him or her, professionals and family caregivers can still interact and create an alliance that promotes collaboration and recovery. Conclusion This article offers benchmarks to facilitate dialogue among people living with a mental health disorder, family caregivers and professionals, and to support their actions around information-sharing and respect for confidentiality in mental health practises. Ultimately, the intention here is to foster collaborative practices that will help improve the quality of mental health services.

Of logos and men: semantic memory impairment for unique entities in a case of semantic variant of primary progressive aphasia

In this study, an individual (NG) with the semantic varient of primary progressive aphasis (svPPA) was assessed with tasks designed to investigate the recognition and activation of semantic knowledge about unique entities. NG had significant difficulties in the recognition of brand names and famous names but was largely unimpaired in the recognition of logos and famous faces. However, she was impaired in tasks requiring the activation of semantic representations of logos, brand names, famous faces, and famous names. These results suggest that the recognition of unique entities results from the interaction of perceptual and conceptual processes and, that the ability to activate semantic information about these entities can be affected in svPPA.

A1 COLONOSCOPY FINDINGS FOLLOWING A FECAL IMMUNOCHEMICAL TEST: A RETROSPECTIVE STUDY ASSESSING THE SCREENING TEST PERFORMANCE

Background

Fecal Immunochemical Testing (FIT) is the preferred test for colorectal cancer screening in the average risk population in Canada.

Aims

This study aims to assess colonoscopy findings in patients who have undergone a FIT within the previous 2 years.

Methods

This retrospective study included all adult patients that have undergone a single diagnostic colonoscopy from March 2013 to March 2016 following a single FIT test at the CIUSSS de l’Estrie, a tertiary hospital. The primary outcome was to evaluate rates of clinically significant lesion when comparing FIT positive (FIT+) to FIT negative (FIT-) colonoscopy, using Quebec’s current threshold of 175 ng/ml of hemoglobin. Secondary outcomes included all other type of lesions, delays between FIT testing and colonoscopy, procedural time, caecal intubation rates and withdrawal time.

Results

Overall, 2230 patients were included, aged 62.0±10.5 years, 55.0% were female and 26.1% had a positive FIT. Patients with a positive FIT had a significantly higher polypectomy rate (62.4% vs 41.3%, p<0.01) and higher number of polyps per patient (2.9±2.5 vs 2.1±1.5, p<0.01). FIT+ had significantly higher rates of adenocarcinoma (3.4% vs 0.7%, p<0.01) with 11 out of 31 patients bearing a negative FIT with the current threshold. No difference was found for sessile serrated polyps (7.8% vs 6.0%, p=0.13). Patients with a FIT+ had significantly higher advanced adenomas (24.0% vs 5.6%, p<0.01), proximal polyps (33.6% vs 22.4%, p<0.01), distal polyps (52.8% vs 28.2%, p<0.01), non-advanced adenomas (38.5% vs 23.9%, p<0.01) and benign polyps (25.1% vs 17.2%, p<0.01). Patients with FIT+ received their colonoscopy 7.5 months earlier than FIT- patients (3.3±2.2 vs 10.8±8.3 months, p<0.01). FIT+ also yielded a significant longer procedural time (28.5±14.1 vs 25.5±12.1, p<0.01) but no difference was noted for caecal intubation rates and withdrawal time (93.3% vs 94.0%, p=0.55 and 14.0±8.4 vs 12.0±7.7, p=0.20 respectively). Results were similar when lowering the threshold to 150, 100, 75 and even 50 ng/ml. 8 patients with an adenocarcinoma had a FIT level lower than 50 ng/ml.

Conclusions

Patients with a colonoscopy and a positive FIT have higher rates of significant findings. Although commonly used for colorectal cancer screening, FIT still failed to detect almost 30% of adenomas and adenocarcinomas found during colonoscopy. It also does not perform very well for serrated polyps. Our data also fails to show an improved yield of the FIT when lowering the its threshold from 175 to 50. There is still a great need for a more sensitive non-invasive colon cancer screening test.

Funding Agencies

None

Short-term post-implantation dynamics of in vitro engineered human microvascularized adipose tissues

Engineered adipose tissues are developed for their use as substitutes for tissue replacement in reconstructive surgery. To ensure a timely perfusion of the grafted substitutes, different strategies can be used such as the incorporation of an endothelial component. In this study, we engineered human adipose tissue substitutes comprising of functional adipocytes as well as a natural extracellular matrix using the self-assembly approach, without the use of exogenous scaffolding elements. Human microvascular endothelial cells (hMVECs) were incorporated during tissue production in vitro and we hypothesized that their presence would favor the early connection with the host vascular network translating into functional enhancement after implantation into nude mice in comparison to the substitutes that were not enriched in hMVECs. In vitro, no significant differences were observed between the substitutes in terms of histological aspects. After implantation, both groups presented numerous adipocytes and an abundant matrix in addition to the presence of host capillaries within the grafts. The substitutes thickness and volume were not significantly different between groups over the short-term time course of 14 days (d). For the microvascularized adipose tissues, human CD31 staining revealed a human capillary network connecting with the host microvasculature as early as 3 d after grafting. The detection of murine red blood cells within human CD31+ structures confirmed the functionality of the human capillary network. By analyzing the extent of the global vascularization achieved, a tendency towards increased total capillary network surface and volume was revealed for prevascularized tissues over 14 d. Therefore, applying this strategy on thicker reconstructed adipose tissues with rate-limiting oxygen diffusion might procure added benefits and prove useful to provide voluminous substitutes for patients suffering from adipose tissue loss or defects.

Impact of TNF and IL-1β on capillary networks within engineered human adipose tissues

Inflammatory cytokines lead to capillary network disorganization and secreted factor modulation within human microvascularized engineered adipose tissues.

Characterization of In Vitro Engineered Human Adipose Tissues: Relevant Adipokine Secretion and Impact of TNF-α

Representative modelling of human adipose tissue functions is central to metabolic research. Tridimensional models able to recreate human adipogenesis in a physiological tissue-like context in vitro are still scarce. We describe the engineering of white adipose tissues reconstructed from their cultured adipose-derived stromal precursor cells. We hypothesize that these reconstructed tissues can recapitulate key functions of AT under basal and pro-inflammatory conditions. These tissues, featuring human adipocytes surrounded by stroma, were stable and metabolically active in long-term cultures (at least 11 weeks). Secretion of major adipokines and growth factors by the reconstructed tissues was determined and compared to media conditioned by human native fat explants. Interestingly, the secretory profiles of the reconstructed adipose tissues indicated an abundant production of leptin, PAI-1 and angiopoietin-1 proteins, while higher HGF levels were detected for the human fat explants. We next demonstrated the responsiveness of the tissues to the pro-inflammatory stimulus TNF-α, as reflected by modulation of MCP-1, NGF and HGF secretion, while VEGF and leptin protein expression did not vary. TNF-α exposure induced changes in gene expression for adipocyte metabolism-associated mRNAs such as SLC2A4, FASN and LIPE, as well as for genes implicated in NF-κB activation. Finally, this model was customized to feature adipocytes representative of progressive stages of differentiation, thereby allowing investigations using newly differentiated or more mature adipocytes. In conclusion, we produced tridimensional tissues engineered in vitro that are able to recapitulate key characteristics of subcutaneous white adipose tissue. These tissues are produced from human cells and their neo-synthesized matrix elements without exogenous or synthetic biomaterials. Therefore, they represent unique tools to investigate the effects of pharmacologically active products on human stromal cells, extracellular matrix and differentiated adipocytes, in addition to compounds modulating adipogenesis from precursor cells.

Magnetic Resonance Imaging of Human Tissue-Engineered Adipose Substitutes

Adipose tissue (AT) substitutes are being developed to answer the strong demand in reconstructive surgery. To facilitate the validation of their functional performance in vivo, and to avoid resorting to excessive number of animals, it is crucial at this stage to develop biomedical imaging methodologies, enabling the follow-up of reconstructed AT substitutes. Until now, biomedical imaging of AT substitutes has scarcely been reported in the literature. Therefore, the optimal parameters enabling good resolution, appropriate contrast, and graft delineation, as well as blood perfusion validation, must be studied and reported. In this study, human adipose substitutes produced from adipose-derived stem/stromal cells using the self-assembly approach of tissue engineering were implanted into athymic mice. The fate of the reconstructed AT substitutes implanted in vivo was successfully followed by magnetic resonance imaging (MRI), which is the imaging modality of choice for visualizing soft ATs. T1-weighted images allowed clear delineation of the grafts, followed by volume integration. The magnetic resonance (MR) signal of reconstructed AT was studied in vitro by proton nuclear magnetic resonance ((1)H-NMR). This confirmed the presence of a strong triglyceride peak of short longitudinal proton relaxation time (T1) values (200 ± 53 ms) in reconstructed AT substitutes (total T1=813 ± 76 ms), which establishes a clear signal difference between adjacent muscle, connective tissue, and native fat (total T1 ~300 ms). Graft volume retention was followed up to 6 weeks after implantation, revealing a gradual resorption rate averaging at 44% of initial substitute's volume. In addition, vascular perfusion measured by dynamic contrast-enhanced-MRI confirmed the graft's vascularization postimplantation (14 and 21 days after grafting). Histological analysis of the grafted tissues revealed the persistence of numerous adipocytes without evidence of cysts or tissue necrosis. This study describes the in vivo grafting of human adipose substitutes devoid of exogenous matrix components, and for the first time, the optimal parameters necessary to achieve efficient MRI visualization of grafted tissue-engineered adipose substitutes.

Creating capillary networks within human engineered tissues: impact of adipocytes and their secretory products

The development of tissue-engineered substitutes of substantial volume is closely associated with the need to ensure rapid vascularization upon grafting. Strategies promoting angiogenesis include the in vitro formation of capillary-like networks within engineered substitutes. We generated both connective and adipose tissues based on a cell sheet technology using human adipose-derived stromal cells. This study evaluates the morphology and extent of the capillary networks that developed upon seeding of human microvascular endothelial cells during tissue production. We posited that adipocyte presence/secretory products could modulate the resulting capillary network when compared to connective substitutes. Analyses including confocal imaging of CD31-labeled capillary-like networks indicated slight differences in their morphological appearance. However, the total volume occupied by the networks as well as the frequency distribution of the structure's volumes were similar between connective and adipose tissues. The average diameter of the capillary structures tended to be 20% higher in reconstructed adipose tissues. Quantification of pro-angiogenic molecules in conditioned media showed greater amounts of leptin (15×), angiopoietin-1 (3.4×) and HGF (1.7×) secreted from adipose than connective tissues at the time of endothelial cell seeding. However, this difference was attenuated during the following coculture period in endothelial cell-containing media, correlating with the minor differences noted between the networks. Taken together, we developed a protocol allowing reconstruction of both connective and adipose tissues featuring well-developed capillary networks in vitro. We performed a detailed characterization of the network architecture within engineered tissues that is relevant for graft assessment before implantation as well as for in vitro screening of angiogenic modulators using three-dimensional models.

Dynamic culture induces a cell type-dependent response impacting on the thickness of engineered connective tissues

Mesenchymal cells are central to connective tissue homeostasis and are widely used for tissue-engineering applications. Dermal fibroblasts and adipose-derived stromal cells (ASCs) allow successful tissue reconstruction by the self-assembly approach of tissue engineering. This method leads to the production of multilayered tissues, devoid of exogenous biomaterials, that can be used as stromal compartments for skin or vesical reconstruction. These tissues are formed by combining cell sheets, generated through cell stimulation with ascorbic acid, which favours the cell-derived production/organization of matrix components. Since media motion can impact on cell behaviour, we investigated the effect of dynamic culture on mesenchymal cells during tissue reconstruction, using the self-assembly method. Tissues produced using ASCs in the presence of a wave-like movement were nearly twice thicker than under standard conditions, while no difference was observed for tissues produced from dermal fibroblasts. The increased matrix deposition was not correlated with an increased proliferation of ASCs, or by higher transcript levels of fibronectin or collagens I and III. A 30% increase of type V collagen mRNA was observed. Interestingly, tissues engineered from dermal fibroblasts featured a four-fold higher level of MMP-1 transcripts under dynamic conditions. Mechanical properties were similar for tissues reconstructed using dynamic or static conditions. Finally, cell sheets produced using ASCs under dynamic conditions could readily be manipulated, resulting in a 2 week reduction of the production time (from 5 to 3 weeks). Our results describe a distinctive property of ASCs' response to media motion, indicating that their culture under dynamic conditions leads to optimized tissue engineering.

2-Methoxyestradiol induce the conversion of human peripheral blood memory B lymphocytes into plasma cells

2-Methoxyestradiol (2ME), an end-metabolite of 17beta-estradiol, is an antiproliferative agent that is currently being tested in clinical trials for cancer treatment. We hereby report that sub-cytotoxic concentrations of 2ME influence the in vitro proliferation of human peripheral blood B lymphocytes. More surprisingly, we have observed that 2ME induces the conversion of CD138(-) B lymphocytes into CD138(+) cells of phenotype similar to immunoglobulin (Ig)-secreting plasma cells. Normal human B lymphocytes expressing CD138 increased in response to 2ME in a dose-dependent fashion, from 2% at baseline up to 31% in cells cultured in the presence of 0.75 microM 2ME. Moreover, most of the converted cells were also CD27(+) and secreted high levels of IgG (151 microg/10(6)cells/24h). IEF studies revealed that conversion occurred in a polyclonal manner. We then exploited this effect of 2ME to gain further insights into the molecular mechanisms that govern changes in transcription factors involved in plasma cells differentiation. Plasma cells generated by 2ME treatment of normal human B lymphocytes expressed elevated levels of IRF4 and reduced levels of Pax5 and Bcl-6. Similarly, levels of XBP-1 and Blimp-1 transcripts were increased. Our results suggest that the differentiation of peripheral blood B lymphocytes into plasma cells requires a similar modulation of transcription factors expression that for tonsil and bone marrow B lymphocytes.

c-Src tyrosine kinase co-associates with and phosphorylates signal transducer and activator of transcription 5b which mediates the proliferation of normal human B lymphocytes

c-Src is the normal human cellular protein homologue of the viral oncogene v-src. c-Src activity was reported recently to increase in CD40-activated human B lymphocytes, suggesting its involvement in proliferation. To elucidate the exact role of c-Src in this process, we investigated the effects of c-Src over-expression on normal B lymphocyte growth. B lymphocytes purified from human peripheral blood were infected with Ad5/F35 vector encoding either a constitutively active c-Src (c-Src/dominant-positive) or a dominant-negative c-Src (c-Src/DN). Little variation of B lymphocytes expansion could be observed between control enhanced yellow fluorescent protein and c-Src/dominant-positive-infected cells. In contrast, over-expression of c-Src/DN results in a 40% inhibition of B lymphocyte expansion. These results suggest that DN c-Src may compete with endogenous c-Src, resulting in partial inhibition of a transcriptional pathway involved in B lymphocyte proliferation. We demonstrate further that c-Src can phosphorylate signal transducer and activator of transcription 5b (STAT5b) on tyrosine 699 and that c-Src and STAT5b co-associate during B lymphocyte proliferation. These results confirm an important role for c-Src in the expansion of normal human B lymphocytes in vitro, in which c-Src may regulate STAT5b in the intracellular signalling pathway important for the proliferation of normal human B lymphocytes.

Does predation risk influence habitat use by northern redbelly dace Phoxinus eos at different spatial scales?

This study investigated the relationship between spatial variations in predation risk and abundance of northern redbelly dace Phoxinus eos at both macroscale (littoral v. pelagic zones) and microscale (structured v. open water habitats in the littoral zone) of Canadian Shield lakes. Minnow traps were placed in both structured and open water habitats in the littoral zone of 13 Canadian Shield lakes, and estimates of the relative predation risk of P. eos in both the pelagic and the littoral zones were obtained from tethering experiments. Results showed that (1) the mean abundance of P. eos in the littoral zone was positively correlated with the relative predation risk in the pelagic zone, (2) P. eos preferentially used structured over open water habitats in the littoral zone and (3) this preference was not related to the relative predation risk in the littoral zone but decreased as the relative predation risk increased in the pelagic zone. At the lake level, these results support the hypothesis that P. eos enter the littoral zone to avoid pelagic piscivores. At the littoral zone level, the results do not necessarily contradict the widely accepted view that P. eos preferentially use structured over open habitats to reduce their predation risk, but suggest that flexibility in antipredator tactics (e.g. shelter use v. shoaling) could explain the spatial distribution of P. eos between structured and open water habitats.

Dead space ventilation parallels changes in scintigraphic vascular obstruction at recurrence of pulmonary embolism and after thrombolytic therapy: a case report

Physiological and alveolar dead space ventilation both increase in pulmonary embolism (PE) in proportion to the severity of vascular obstruction. The case of a patient with recurrent PE while on heparin therapy is presented. The recurrence was characterized clinically by severe pulmonary vascular obstruction and right heart dysfunction. The patient was treated with thrombolytic therapy, with excellent clinical and scintigraphic resolution. Dead space ventilation measurements at baseline, at the time of recurrence and after thrombolytic therapy are presented. The potential utility of dead space ventilation measurements for PE diagnosis and management are discussed.

Increase in antilipoperoxidant activity of plasma as a consequence of an inflammatory reaction induced by subcutaneous turpentine in the rabbit

In the rabbit, an acute inflammatory reaction triggered by the subcutaneous administration of turpentine induces in hepatic tissues an oxidative stress, as well as a decrease in activity of enzymatic scavengers of reactive oxygen species (ROS). The objective of this study was to investigate, the repercussions of a local inflammatory reaction on the antioxidant capacity and markers of systemic oxidative stress in plasma. To this purpose, rabbits received a.s.c. injection of turpentine (5 mL/kg) or NaCl 0.9% (w/v). Blood samples were collected at different times during the 48 hours of the experiment to evaluate: firstly, the antilipoperoxidant activity of plasma by measuring the inhibition of autoxidation of brain homogenate, and the concentrations of tocopherol and ascorbic acid; secondly, the severity of oxidative stress in plasma by assaying the concentration of thiobarbituric acid reactive substances (TBARS), and the concentration of ascorbyl radical. The results show that the antilipoperoxidant capacity of plasma gradually increased to be 167% higher than baseline values (p < 0.05) after 48 hours of experiment. alpha-Tocopherol and ascorbic acid levels increased by 49% and 80%, respectively (p < 0.05) during the first 24 hours. Lipid peroxidation continuously increased to be 98% higher than baseline values (p < 0.05) at 48 hours, while ascorbyl radical levels were not modified (p < 0.05). In summary, an acute local inflammatory reaction causes a steady progression of oxidative stress, while it stimulates the antilipoperoxidant activity of plasma, to which alpha-tocopherol and ascorbic acid appear to contribute, essentially early in the inflammation.

Acute moderate hypoxia in conscious rabbits: effect on hepatic cytochrome P450 and on reactive oxygen species

This study aimed to document whether acute moderate hypoxia modifies the amount and activity of hepatic cytochrome P450 and in addition, induces changes in the production or the ability to neutralize oxygen reactive species (ORS). Rabbits were exposed to a low partial pressure of oxygen (12%) for 8 or 24 h, killed, and the amount and activity of cytochrome P450, lipid peroxidation, microsomal chemiluminescence and enzymatic scavenger activity were assessed in the liver. After 8 h of hypoxia, total amount but not the activity of cytochrome P450 was decreased, although after 24 h of hypoxia, both the amount and the activity of cytochrome P450 were decreased. Hypoxia for 8 h increased the activity of glutathione peroxidase. However, after 24 h of hypoxia, lipid peroxidation, microsomal chemiluminescence and superoxide dismutase activity were increased, while hepatic glutathione and glutathione peroxidase activity were reduced, modifications that suggest an enhanced presence of ORS. In in-vitro studies, an ORS generating system reduced the activity of cytochrome P450 and enhanced lipid peroxidation of hepatic microsomal membranes, supporting the view that ORS can impair cytochrome P450. The results of the present study show that hypoxia induces changes in the amount and activity of cytochrome P450, as well as in the production or the ability to neutralize ORS, and that these changes are time-dependent.

Inflammation-induced decrease in hepatic cytochrome P450 in conscious rabbits is accompanied by an increase in hepatic oxidative stress

It has been documented that cytokines can induce the formation of reactive oxygen species (ROS) in the liver, and that an inflammatory reaction can locally increase the production of ROS, but it remains unknown whether in vivo a subcutaneous (s.c.) inflammatory reaction can induce the formation of ROS in the liver. To determine in vivo whether an inflammatory reaction, able to decrease the amount of hepatic cytochrome P450, enhances the presence of ROS in the liver, turpentine was injected s.c. to rabbits, which were sacrificed 48 hours later. Control rabbits received saline s.c. The amount and activity of cytochrome P450, as well as several parameters reflecting the presence of ROS were assessed in the liver. Total amount of cytochrome P450 was reduced, as was its activity, assessed by the rates of hydroxylation of aniline and of demethylation of aminopyrine. Moreover, lipid peroxidation increased, while the activity of the enzymatic scavengers, i.e. catalase, glutathione peroxidase and superoxide dismutase decreased. In addition, hepatic concentrations of reduced glutathione were diminished. On the other hand, the activity of the xanthine oxidase system was enhanced by almost 200%. These results strongly suggest an increased presence of ROS. The changes in the amount of cytochrome P450 were inversely correlated with lipid peroxidation. In conclusion, these results show that in vivo an inflammatory reaction, that reduces total cytochrome P450 and its activity, produces simultaneously an oxidative stress in the liver.

Nocturnal positive-pressure nasal ventilation for respiratory failure during pregnancy

Images

Molecular structure of opiate alkaloids. Part I. Crystal structure of two 16-alkyl analogues of thebaine and oripavine

The crystal structures of two 16-alkyl thebaine and oripavine analogues are described, in an attempt to put forward the particular requirements of these compounds to interact with the opiate receptor. Conformational congruencies accounting for the very high potency of these compounds are also emphasized.In light of the crystal structures, the influence of the 16-alkyl substitution is discussed, as well as the differentiation in the agonist activity observed between diastereomers at C(19) characterizing these classes of opioids.Significant distortions in the condensed ring system and the existence of an intramolecular hydrogen bonding are the main geometrical observations. They are invoked to account for particular modulations in the analgesic activity.

Use of egg washwater pH to prevent survival of Salmonella at moderate temperatures

The survival and thermal resistance of Salmonella typhimurium N+L141083 was examined in egg washwater at moderate temperatures over a range of pH values. Salmonella were able to grow at 38 and 42 C when washwater pH was less than or equal to 9.5, but substantial lethality was noted at greater than or equal to pH 10. At pH 10.5 and 11, Salmonella were eliminated within 5 hr. At 6 C, Salmonella levels were maintained for 18 hr without lethality up to pH 11. At pH 11, some lethality was noted after 5 hr. A D42 value at pH 7.0 could not be calculated, but at pH 10, a value of 40.8 sec was determined. Narrow range pH paper (pH 8 to 10) responded to egg washwater contact at or above pH 10 with a clear color reaction. Below pH 10, the paper signalled the need for addition of alkaline detergent to prevent the growth of Salmonella.

A single glutamyl-tRNA synthetase aminoacylates tRNAGlu and tRNAGln in Bacillus subtilis and efficiently misacylates Escherichia coli tRNAGln1 in vitro

In the presence or absence of its regulatory factor, the monomeric glutamyl-tRNA synthetase from Bacillus subtilis can aminoacylate in vitro with glutamate both tRNAGlu and tRNAGln from B. subtilis and tRNAGln1 but not tRNAGln2 or tRNAGlu from Escherichia coli. The Km and Vmax values of the enzyme for its substrates in these homologous or heterologous aminoacylation reactions are very similar. This enzyme is the only aminoacyl-tRNA synthetase reported to aminoacylate with normal kinetic parameters two tRNA species coding for different amino acids and to misacylate at a high rate a heterologous tRNA under normal aminoacylation conditions. The exceptional lack of specificity of this enzyme for its tRNAGlu and tRNAGln substrates, together with structural and catalytic peculiarities shared with the E. coli glutamyl- and glutaminyl-tRNA synthetases, suggests the existence of a close evolutionary linkage between the aminoacyl-tRNA synthetases specific for glutamate and those specific for glutamine. A comparison of the primary structures of the three tRNAs efficiently charged by the B. subtilis glutamyl-tRNA synthetase with those of E. coli tRNAGlu and tRNAGln2 suggests that this enzyme interacts with the G64-C50 or G64-U50 in the T psi stem of its tRNA substrates.

Lactose transport in Streptococcus mutans: isolation and characterization of factor IIIlac, a specific protein component of the phosphoenolpyruvate-lactose phosphotransferase system

The transport of lactose in Streptococcus mutans is mediated via an inducible phosphoenolpyruvate-lactose phosphotransferase system. This system requires for catalytic activity a membrane fraction (enzyme II), two general proteins called enzyme I and HPr, and a soluble specific protein termed factor IIIlac. This protein factor was purified from S. mutans ATCC 27352 by chromatographies on DEAE-cellulose, hydroxylapatite, Ultrogel AcA 34, and phosphocellulose. The purified protein migrated as a single band with a molecular weight of 10,000 on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and urea. The molecular weight calculated from the amino acid composition was 10,541. Gel filtration of the native protein gave a molecular weight of 41,500. Its isoelectric point was ca. 4.70. A specific antiserum was prepared against purified factor IIIlac. Immunodiffusion experiments revealed that only cellular extracts from lactose-grown cells contained factor IIIlac. A cross-reaction was observed with all of the S. mutans strains tested as well as with Streptococcus sanguis 10556, Streptococcus lactis 11454, and Staphylococcus aureus 6538. No precipitin band was observed with extracts of Streptococcus salivarius, Streptococcus faecalis, Lactobacillus casei, and Bacillus subtilis.

Purification of proteins similar to HPr and enzyme I from the oral bacterium Streptococcus salivarius. Biochemical and immunochemical properties

The phosphoenolpyruvate:sugar phosphotransferase system (PTS) is made of several proteins. Two of them are designated general proteins because they are required for the transport and phosphorylation of all sugars of the PTS. These two proteins are found in the soluble fraction of cellular extracts and are termed HPr and enzyme I (EI). We reported in this work the purification and the characterization of these two proteins from Streptococcus salivarius ATCC 25975. HPr was purified by DEAE-cellulose chromatography, molecular sieving on Ultrogel AcA44, and carboxymethylcellulose chromatography. Sodium dodecyl sulfate electrophoresis in the presence of urea revealed a single band with a molecular weight of 6700. The protein contained no tryptophan and had a pI of 4.8. The purification scheme of EI was as follows: DEAE-cellulose chromatography, hydroxylapatite chromatography, DEAE-Sephadex A-50 chromatography, preparative electrophoresis, and molecular sieving on Ultrogel AcA34. The five-step purification for EI produced a 199-fold purified preparation with a specific activity of 530 mumol of HPr phosphorylated per minute per milligram of protein at 37 degrees C. The fraction obtained after filtration on Ultrogel AcA34 gave one band (68 000) on sodium dodecyl sulfate - polyacrylamide gel electrophoresis. The molecular weight of the native enzyme determined by gel filtration at 4 degrees C was 135 000, suggesting that it was a dimer. Enzyme I had a pI of 4.2, a pH optimum of 6.7, a Km for HPr of about 27 microM, a Km for phosphoenolpyruvate of 0.48 mM, and kinetics that were consistent with a Ping-Pong mechanism. Evidence had been obtained which indicated that S. salivarius enzyme I was antigenically very similar to enzyme I from various strains of Streptococcus mutans, but not to the enzyme from Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, and Escherichia coli.

The monomeric glutamyl-tRNA synthetase from Bacillus subtilis 168 and its regulatory factor. Their purification, characterization, and the study of their interaction

The glutamyl-tRNA synthetase from Bacillus subtilis has been purified to homogeneity. It is a monomer of Mr = 65,500 whose NH2-terminal sequence is Met-Asn-Glu-Val-Arg-Val-Arg-Tyr-Ser-Pro-Ser-Pro-Thr-Gly-His-Leu. The number of tryptic peptides indicates the absence of a significant amount of sequence duplication. Under certain conditions, this monomeric enzyme is co-purified with a polypeptide beta of Mr = 46,000, which increases the affinity of the enzyme about 10-fold for glutamate and for ATP, and stabilizes it against heat inactivation. gamma-Globulins prepared against the monomeric enzyme can inhibit completely the glutamyl-tRNA synthetase activity of a B. subtilis extract and precipitate from this extract both the monomeric enzyme and the regulatory factor beta. These anti-alpha immunoglobulins do nt precipitate pure beta. These results show that the glutamyl-tRNA synthetase of B. subtilis has a structure similar to that of the Escherichia coli enzyme (Lapointe, J., and Söll, D. (1972) J. Biol. Chem. 247, 4966-4974) and indicate that the beta factor has a function in the regulation of glutamyl-tRNA biosynthesis in vivo.

Effect of gramicidin D on the acidogenic properties of oral streptococci and human dental plaque

The effect of gramicidin D, Gramicidin S, and carbonylcyanide p-trifluoromethoxyphenyl hydrazone on the glycolysis of various oral streptococci was investigated. Gramicidin D was the most effective and inhibited the glycolysis of all the streptococci studied in the presence of the most common sugars found in man's diet (sucrose, lactose, glucose, and fructose). A concentration of 2.5 X 10(-6) M gramicidin D was sufficient to decrease significantly the rate of glycolysis of human dental plaque in the presence of sucrose. The use of this ionophore as a caries preventive agent is discussed.